The present invention relates to a transducer that measures displacement along and about three orthogonal axes.
Transducers or load cells for determining forces along and moments about orthogonal axes are known. Two examples of such load cells are disclosed in U.S. Pat. Nos. 4,640,138 and 4,821,582. These transducers have been effective in providing accurate force and moment data acting through a wheel assembly mounted to a vehicle spindle. This data is useful in the design and manufacture of vehicles and/or vehicle systems.
Although current load cells are effective tools, there is a need to obtain further information about the tire and wheel assembly as it travels down a road. In particular, there is a need to provide an improved apparatus and method for measuring displacement of the vehicle spindle, preferably, with respect to six degrees of freedom.
In order to measure displacement of a vehicle spindle with respect to an orthogonal coordinate system, a body is mounted to the vehicle spindle. A plurality of accelerometers are coupled to the body and provide acceleration signals responsive to acceleration of the body. A calculation circuit is coupled to the plurality of accelerometers and is adapted to receive and convert the acceleration signals to displacement signals. The displacement signals are indicative of displacement of the body, and thus, the vehicle spindle with respect to the orthogonal coordinate system.
Another aspect of the present invention is a method for measuring displacement of a vehicle spindle with respect to an orthogonal coordinate system. A body is mounted to the vehicle spindle. The body includes accelerometers to measure acceleration of the body. Displacement of the body and the vehicle spindle is calculated depending on the measured acceleration.